This is an application for a Zeiss inverted microscope with precision motorized stage and sensitive CCD camera for time-lapse, live-cell imaging. The microscope will be used as a dedicated station for constant-focus time-lapse imaging with DIG and fluorescence optics. The precision AS) motorized piezo microscope stage and the Zeiss environmental control system will allow us to image cells at constant focus under physiological conditions for hours or days at a time. This stage will also be used to prepare time-lapse sequences of cells at different locations during the same imaging session. The sensitive Photometrics Cascade CCD camera will significantly reduce photobleaching and maintain cell viability. This application is based on a critical need to monitor cell responses over time by time-lapse recording and will serve a large NIH-funded community. [unreadable] [unreadable]